|Location Map ( geo)|
|28th September 1978|
The Friarton Bridge forms part of the Perth western bypass and was one of the last sections of the M90 to be completed. It was the largest structure on the M90 until the Queensferry Crossing was completed in 2017. The bridge is a bit unusual in design as it is effectively a dual carriageway under motorway restrictions but not unusual for the M90 as 8 miles of it has no hard shoulders anyway. Originally, it was classed as the M85 until the A90 number was extended northwards so it became the M90.
The bridge is a concrete and steel box girder bridge and makes a large impact on the surrounding landscape. The bridge was designed by the Cleveland Bridge Company, and was strengthened in 1990 to cope with the increase in traffic.
The bridge consists of 9 spans across the Tay Valley, and is effectively two parallel structres, one for either carriageway. The deck is banked on the surved southern approach, necessitating shallow trapezoid box girders. These grow considerably in depth at the piers either side of the main river span, across which the road is level, albeit with a slight camber. The box girders then form shallow arches over the river. There are 6 spans to the south of the river and two to the north.